Nitrile-butadiene rubber (NBR) is an oil resistant elastomer used in automotive applications. It has poor high temperature properties. The recommended continuous use temperature is between 100.COPYRGT.-125.degree. C. Commercially available hydrogenated NBR (HNBR) addresses the need for a higher use temperature, oil resistant elastomer having a continuous use temperature up to about 150.degree. C.
Removal of the backbone unsaturation in NBR by hydrogenation increases the heat resistance of the polymer while maintaining its low temperature and oil resistance properties. HNBR is mainly a random copolymer of ethylene and acrylonitrile HNBR compositions that contain up to 40 weight percent bound acrylonitrile and 60 weight percent hydrocarbon segments have high oil resistance and good low temperature properties. Higher acrylonitrile oil resistance, but would be detrimental to low temperature properties.
Bronstert et al. U.S. Pat. No. 3,673,28, June 27, 1972) relates to a process for the hydrogenation of polymers containing double bonds in solution and in the presence of a catalyst complex comprising:
A. a compound of iron, cobalt or nickel,
B. an organo-aluminum compound, and
C. hexaalkylphosphhoric acid triamide as activator.
Polymers of diene hydrocarbons contain double bonds in the backbone. These double bonds may be hydrogenated by conventional processes. Products which are wholly or partly hydrogenated in this way are superior to non-hydrogenated polymers in that they possess improved resistance to aging and are particularly resistant to oxidative degradation. In the case of block copolymers of dienes and vinyl aromatic compounds, in particular, the hydrogenated products also show improved tensile properties and mechanical strength. When only partially hydrogenated, the diene polymers may be vulcanized. Such vulcanizates possess a higher tensile strength and a lower glass temperature than vulcanizates of non-hydrogenated diene polymers.
Yoshimoto et al U.S. Pat. No. 3,625,927 Dec. 7, 1971) relates to a catalyst for hydrogenating a high molecular weight polymer having hydrogenatable unsaturated bonds. This catalyst is suitable for hydrogenation of the polymer is a viscous solution form and comprises a reaction product of (1) a metal chelate compound of nickel, cobalt, or iron, with (2) an organic metallic reducing agent in said chelate compound. The chelating agent is attached to the metal by a pair of nitrogen atoms and an oxygen atom.
Yoshimoto et al U.S. Pat. No. 3,531,450 Sept. 29, 1970) relates to a new hydrogenation catalyst consisting of three catalytic components and a process for hydrogenating polymers by the use of said catalyst. This three-component catalyst consists of (1) at least one kind of an unsaturated hydrocarbon selected from the group consisting of an olefinically unsaturated hydrocarbon and an acetylenically unsaturated hydrocarbon, (2) at least one kind of an organic compound of the metal selected from the group consisting of nickel, cobalt and iron, and (3) at least one kind of a metal compound reducing agent.